The present invention relates to improvements for highly elastic shaft couplings.
Highly elastic shaft couplings are, for example, constructed in that two rigid annuli are disposed in concentric, radial alignment to each other, and an elastic layer or elements are interposed between them. The inner annulus is, for example, connected to the driving part and the outer annulus is connected to the drive part of the system which is drivingly interconnected by that coupling. In some cases such a coupling is used in a clutch, e.g. between the driving shaft and the active clutch.
Such elastic couplings are used, for example, in Diesel engine power plants for reducing particularly low frequency, rotational, i.e. torsional oscillations so that the plant could be run supercritically. These arrangements have been operated successfully as the inherent attenuation provided by the rubber used in the coupling sufficed, and the coupling as a whole was used only to an insignificant extent for damping the system.
Diesel-engineering has lead to a lowering of the weight-to-power ratio so that, relatively speaking, higher energizing forces coact with smaller masses in the system which is unfavorable as far as oscillations are concerned. Thus, interaction at higher frequencies in the crank shaft becomes so large that the regular oscillation dampers and attenuators of the engine are insufficient and the elastic coupling has to more actively participate in the damping. The U.S. Pat. No. 3,791,497 describes an electromagnetic system which relieves a double cone friction clutch with a highly elastic coupling portion from these oscillations. The device as disclosed therein operates quite satisfactory, but requires a separate electric circuit and components with current feeding, etc., for just that purpose.
The older German Pat. No. 905,562 discloses attenuation by means of parallelly operating elastic couplings, but it was found that the performance of the system does not improve significantly with regard to oscillations. This patent mentions also so-called omega springs to be used in the coupling, and pressurized hydraulic oil is employed for attenuation, but that method requires also a separate hydraulic system, control thereof, etc.